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United States Patent |
5,527,235
|
Kuroda
,   et al.
|
June 18, 1996
|
Transmission-controlling system
Abstract
A transmission-controlling system capable of controlling a transmission of
a vehicle having both an automatic transmission (AT) and an anti-lock
brake system (lBS), without damaging the ABS function is disclosed, in
which both a change-speed graph for normal operation and a change-speed
graph for acquiring automatic engine brake are incorporated in an AT
controller and, when a signal noticing that ABS is in operation is not
given from an ABS controller, the AT controller functions to shift gear
speed according to the change-speed graph for aquiring automatic engine
brake to thereby attain automatic engine brake and, when the signal
noticing that ABS is out of operation, the AT controller functions to
shift gear speed according to the change-speed graph for normal operation.
In the latter case, the automatic engine brake is not acquired, and hence
the ABS function is not possibly damaged, and the vehicle does not receive
a severe shock.
Inventors:
|
Kuroda; Kouichi (Yokohama, JP);
Adachi; Tomoyoshi (Machida, JP);
Kato; Masaya (Yokohama, JP)
|
Assignee:
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Isuzu Motors Limited (Tokyo, JP)
|
Appl. No.:
|
409600 |
Filed:
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March 24, 1995 |
Foreign Application Priority Data
Current U.S. Class: |
477/94 |
Intern'l Class: |
F16H 059/04 |
Field of Search: |
477/92,94,96
|
References Cited
U.S. Patent Documents
4971400 | Nov., 1990 | Jonner | 303/110.
|
5109962 | May., 1992 | Sato | 192/4.
|
5113718 | May., 1992 | Sato | 180/197.
|
5125490 | Jun., 1992 | Suzumura et al. | 475/86.
|
5262952 | Nov., 1993 | Tsuyama et al. | 364/426.
|
Primary Examiner: Wright; Dirk
Attorney, Agent or Firm: Spencer & Frank
Claims
What is claimed is:
1. A transmission-controlling system having a sensor for detecting
divergence of a throttle valve, a sensor for detecting vehicle speed, a
hydraulic mechanism for shifting gear, and an AT controller which has
change-speed graphs for determining a proper gear based on the detected
divergence of a throttle valve and the vehicle speed and controls the
hydraulic mechanism to shift gear, in which the AT controller has both a
change-speed graph for normal operation and a change-speed graph for
acquiring automatic engine brake and is constituted to receive a signal
whether an anti-lock brake system is in operation or not and, when a
signal noticing that ABS is in operation is given to the AT controller, it
selects the change-speed graph for normal operation to control the
transmission and, when such signal is not given, it selects the
change-speed graph for acquiring engine brake to control the transmission.
Description
DESCRIPTION
BACKGROUND OF THE INVENTION
This invention relates to a transmission-controlling system of a vehicle
having both an automatic transmission (hereinafter abbreviated as "AT")
and an anti-lock brake system (hereinafter abbreviated as "ABS").
In AT vehicles, divergence of a throttle valve of an engine and vehicle
speed are detected, a proper speed gear is determined by using both data
signals with reference to a predetermined change-speed graph, and the
transmission is controlled to shift to the determined speed gear.
FIG. 2 shows an example of a change-speed graph for normal operation, in
which vehicle speed is plotted as abscissa and divergence of throttle
valve as ordinate. Solid line I shows a 3.fwdarw.4 shift-up curve (a curve
showing the time of shifting up the gear from 3rd speed gear to 4th speed
gear). When a vehicle droven with a 3rd speed gear acquires an increased
vehicle speed in a manner of crossing the shift-up curve I as shown by the
arrow A in FIG. 2, the transmission is controlled to select the 4th speed
gear.
Dotted line II shows a 4.fwdarw.3 shift-down curve (a curve showing the
time of shifting down the gear from 4th speed gear to 3rd speed gear).
When a vehicle droven with a 4th speed gear acquires a decreased vehicle
speed in a manner of crossing the shift-down curve II as shown by the
arrow B in FIG. 2, the transmission is controlled to select the 3rd speed
gear.
Although FIG. 2 shows only two curves relating to 3rd and 4th speeds, there
exist curves relating to 1st speed, 2nd speed, etc.
On the other hand, AT vehicles for business use suffer more abrasion of a
brake lining than AT passenger vehicles because they are droven in a
heavily loaded state with putting on brake many times. Therefore, in order
to reduce the abrasion, a so-called "automatic engine brake control" has
been considered which functions to automatically acquire engine brake when
application of brake is necessary. To be specific, the automatic engine
brake control is to control so that, when a throttle valve position of a
vehicle droven with a 4th speed gear at a speed within a predetermined
range is restored to the idle position, the speed gear is automatically
shifted down to the 3rd speed gear.
FIG. 3 shows an example of a change-speed graph for acquiring automatic
engine brake. Symbols used in FIG. 3 correspond to those used in FIG. 2.
As can be immediately seen by comparing with FIG. 2, both solid line I and
dotted line II in FIG. 3 make a turn to the right at a certain small
throttle valve divergence in a direction in which vehicle speed increases
and, after advancing a certain distance in a direction almost parallel to
the abscissa, they again make a turn in a downward direction almost
parallel to the ordinate. Change-speed graphs of such patterns can attain
the automatic engine brake control.
For example, when a throttle valve of a vehicle droven at a speed within
the range of the change-speed curve II being almost parallel to the
abscissa is restored to the idle position (at which the divergence of the
throttle valve is zero on the ordinate), the throttle valve divergence
crosses the change-speed curve II from above (4th speed side) to below
(3rd speed side) as shown by the arrow C, thus the transmission being
controlled to shift down to the 3rd speed gear to acquire engine brake. In
the normal operation shown by FIG. 2, the divergence change as shown by
the arrow C would not cross the change-speed curve II, and hence no
shifting down to the 3rd speed gear takes place. Accordingly, a required
brake must be obtained by pedaling a foot brake, leading to a rapid
abrasion of a brake lining.
On the other hand, there is known ABS as a system for not causing slip of
wheels upon putting on brake. This is a system which detects the rotating
speed of wheels and, when wheels are nearly locked, automatically reduces
the braking power to thereby prevent wheels from being locked. This ABS is
also often loaded on AT vehicles.
In the conventional transmission-controlling system for acquiring automatic
engine brake, this system functions independently from ABS. Therefore,
there have been a problem that ABS function might be damaged and a problem
that a serious shock is produced upon shifting gear.
When a driver removes his foot from the accelerator pedal during driving a
vehicle at a 4th speed, the throttle valve is restored to the idle
position, and the transmission-controlling system for acquiring engine
brake functions to shift down the gear to a 3rd speed gear. Thus, each
wheel receives a braking power due to engine brake. However, if this
happens during the period wherein ABS is in operation (to reduce the
braking power on each wheel), ABS function might be damaged.
In addition, when automatic engine brake is acquired to shift down the gear
to the 3rd speed gear upon ABS being in operation, a serious shock is
produced upon shifting of gear if the rotation number on the engine side
is greatly different from that on the transmission side. If rotating
wheels are in contact with a split-surfaced road (for example, a road
separated into a frozen surface-having portion and a non-frozen
surface-having portion), vehicle stability in the running direction is
damaged by the shock to possibly cause a traffic accident.
The subject of this invention is to solve the abovedescribed problems.
SUMMARY OF THE INVENTION
The above-described subject is solved by a transmission-controlling system
having a sensor for detecting divergence of a throttle valve, a sensor for
detecting vehicle speed, a hydraulic mechanism for shifting gear, and an
AT controller which has change-speed graphs for determining a proper gear
based on the detected divergence of a throttle valve and the vehicle speed
and controls the hydraulic mechanism to shift gear, in which the AT
controller has both a change-speed graph for normal operation and a
change-speed graph for acquiring automatic engine brake and is constituted
to receive a signal whether an anti-lock brake system is in operation or
not and, when a signal noticing that ABS is in operation is given to the
AT controller, it selects the change-speed graph for normal operation to
control the transmission and, when such signal is not given, it selects
the change-speed graph for acquiring engine brake to control the
transmission.
Since the AT controller controls gear shifting according to the
change-speed graph for acquiring automatic engine brake during the period
in which ABS does not function, the automatic engine brake control is
conducted if the accelerator pedal is eased up to restore the throttle
valve to the idle position. However, upon receiving a signal noticing that
ABS is in operation, the AT controller now controls gear shifting
according to the change-speed graph for normal operation, the automatic
engine brake control is not conducted. Thus, there is no possibility of
ABS function being damaged and no possibility of a serious shock being
given to the vehicle.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a drawing showing a transmission-controlling system of the
present invention.
FIG. 2 is a change-speed graph for normal operation.
FIG. 3 is a change-speed graph for acquiring automatic engine brake.
FIG. 4 is a flow chart illustrating how to control the transmission
according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION
An embodiment of the present invention is now described in detail by
reference to the drawings. In FIG. 1, numeral 1 designates an engine, 2 a
fan, 3 a wheel, 4 a wheel speed sensor, 5 a sensor for detecting
divergence of throttle valve, 6 a throttle valve, 7 an accelerator pedal,
8 AT (an automatic transmission), 9 a hydraulic pipe for braking, 10 a
hydraulic actuator unit, 11 a hydraulic mechanism for gear shifting, 12 a
propeller shaft, 13 a vehicle speed sensor, 14 an AT controller, 15 an ABS
controller, 16 a first-shift solenoid actuating signal, and 17 a
second-shift solenoid actuating signal.
The AT controller 14 automatically controls gear shifting in AT 8 according
to a predetermined change-speed graph. The ABS controller 15 controls
braking power so that each wheel will not be locked to cause slipping.
Divergence of the throttle valve 6 can be changed by changing the degree
of treadling the accelerator pedal 7. The sensor 5 for detecting
divergence of throttle valve detects divergence of the throttle valve.
The hydraulic mechanism 11 for gear shifting is attached to the AT 8, and
functions to properly actuate two gear-shifting solenoids (not shown) for
shifting gears to desired positions. The hydraulic actuator unit 10 gives
a hydraulic pressure to each wheel via the hydraulic pipe 9 for braking,
thus adjusting braking power. The wheel speed sensor 4 applied to each
wheel 3 detects rotation speed of each wheel.
A signal from the wheel speed sensor 4 is given to the ABS controller 15.
Upon receiving the signal, the ABS controller 15 gives a controlling
signal to the hydraulic actuator unit 10 to adjust braking power so that
each wheel 3 will not be locked.
The AT controller 14 has both a normal change-speed graph (see FIG. 2) and
a change-speed graph for acquiring automatic engine brake (see FIG. 3) as
base change-speed graphs for controlling transmission. It decides a proper
speed gear based on vehicle speed detected by the vehicle speed sensor 13
and divergence of throttle valve detected by the sensor 5 for detecting
divergence of throttle valve by referring to the two graphs, and gives a
first-shift solenoid actuating signal 16 and a second-shift solenoid
actuating signal 17 to the hydraulic mechanism 11 for gear shifting.
The ABS controller 15 is constituted so that a signal noticing whether ABS
control is conducted or not (hereinafter referred to as "ABS operation
signal") is transferred from the ABS controller 15 to the AT controller
14. In FIG. 1, an arrow from ABS controller 15 to AT controller 14 shows
the route for transferring the ABS operation signal, a feature of the
present invention is that, when a signal noticing that ABS is in operation
is given, a change-speed graph for normal operation is selected and, when
no such signal is given, a change-speed graph for acquiring automatic
engine brake is selected.
a more detailed description is given below.
FIG. 4 is a flow chart illustrating how the transmission is controlled in
the present invention.
Step 1--Detections of factors on conditions of vehicles necessary for
controlling the transmission. For example, it is detected whether the
vehicle is in a running range. Similarly, gear position, vehicle speed,
etc. are detected. The running range and gear position can be detected by
means of a gear position sensor provided within AT 8.
Step 2--Before initiation of the transmission control, it is detected
whether ABS controller 15 is in operation or not. This detection is
conducted by checking whether the ABS operation signal from ABS controller
15 indicates the value which notices that ABS is in operation or not.
Step 3--If ABS is in operation, the automatic engine brake control is not
conducted. Otherwise, there arises the problem of ABS function being
damaged or the like as has been described hereinbefore. Therefore, a
change-speed graph for normal operation is selected in this case.
Step 4--If ABS is not in operation, it is better to conduct automatic
engine brake control from the standpoint of reducing abrasion of a brake
lining. Hence, a change-speed graph for acquiring automatic engine brake
is selected.
Step 5--The detected vehicle speed and the detected divergence of throttle
valve are applied to the selected change-speed graph to determine a
desired speed gear.
Step 6--AT controller 14 gives a first-shift solenoid actuating signal 16
and a second-shift solenoid actuating signal 17 to hydraulic mechanism 11
for gear shifting so as to select the determined gear. The determined gear
is thus shifted to a proper position by combination of on and off of the
first and the second shift solenoid.
The invention may be embodied in other specific forms without departing
from the spirit or essential characteristics thereof. The present
embodiment is therefore to be considered in all respects as illustrative
and not restrictive, the scope of the invention being indicated by the
appended claim rather than by the foregoing description, and all the
changes which come within the meaning and range of equivalency of the
claim are therefore intended to be embraced therein.
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